The extracardiac conduit Fontan procedure is widely regarded as the preferred approach for definitive palliation of single ventricle anomalies by many surgeons and centers [1]. This technique offers several advantages, including improved hemodynamics, technical simplicity, possible avoidance of aortic cross-clamping, elimination of intracardiac prosthetic materials (thereby reducing thrombogenic risk), a lower incidence of arrhythmias due to fewer atrial sutures, and reduced pulmonary vein compression.

Limitations of this technique persist include the difficulty of creating and maintaining a patent fenestration and the limited venous access to the atrium for pacing or intracardiac interventional procedures.

Possible approaches include traversing an existing fenestration, performing a transbaffle or transcaval puncture, or employing a retrograde aortic approach with remote magnetic navigation.

The presence of a prior Fontan fenestration does not guarantee persistent patency, as fenestrations across extracardiac conduits are prone to spontaneous closure with the time.

Having a defined anatomical landmark for fenestration can therefore be highly advantageous.

We present herein a technical modification of the standard extracardiac Fontan procedure, incorporating a prebuilt fenestration specifically designed to facilitate future access to the right atrium by interventional cardiologists or electrophysiologists, improving procedural flexibility and long-term management options.

Since January 2016, we have adopted this technique, which has now become the standard practice in all Fontan procedures performed at our institution.

Cardiopulmonary bypass is established via direct cannulation of the aorta and both caval veins. The procedure is routinely conducted on a beating heart under normothermia. Alternatively, depending on the underlying cardiac anatomy, the Fontan procedure may be conducted under cardioplegic cardiac arrest while maintaining normothermia.

A polytetrafluoroethylene (PTFE) conduit is interposed between the inferior vena cava and the pulmonary artery confluence. To facilitate future percutaneous access, a radio-opaque marker is positioned around the fenestration.

The fenestration can be created either by applying four metallic clips at the cardinal points or by placing circular metallic sutures. The right atrial free wall is anastomosed to the conduit surrounding the fenestration using a continuous running suture, leaving a small margin around the orifice to prevent inadvertent closure. The fenestration itself remains untouched by the suture line, with the marker fully incorporated within it (Fig. 1).

Surgical steps of the extracardiac fenestrated Fontan procedure: creation of a radio-opaque landmark around the fenestration; incorporation of the landmark into the suture line; final result of the completed extracardiac fenestrated Fontan

The same technique is applied even in cases where direct fenestration is not performed, with the marker being left in place and sutured to the atrial wall to facilitate potential future procedures.

All patients had an uneventful postoperative course and were discharged on oral anticoagulation therapy for one year, after which it’s replaced with aspirin.

During follow-up, the clinical utility of this technique was demonstrated in a patient with unbalanced complete atrioventricular canal, who underwent a fenestrated extracardiac Fontan in 2020. The patient presented with recurrent syncopal episodes and severe exercise-induced desaturation over the preceding year. Cardiac catheterization was indicated to assess the potential closure of the fenestration.

CT scan or MRI imaging was not required.

The procedure involved right femoral venous access for device delivery, left femoral venous access for contrast injection and pressure sampling, and right femoral arterial access for hemodynamic monitoring.

The radio-opaque marker enabled immediate localization of the fenestration (Fig. 2).

Intra-procedural fluoroscopic views showing successful placement and radiographic detectability of our developed marker

An 18 mm AGA balloon occlusion test was performed, resulting in a marked increase in oxygen saturation from 75% to 85–90%, without any rise in pulmonary artery pressure. The fenestration was then accurately measured, allowing for selection of an appropriately sized closure device.

An 18 mm Amplatzer Talisman PFO occluder was successfully implanted (Fig. 3).

Fluoroscopic views showing the deployed 18 mm Amplatzer Talisman PFO occluder

Notably, incorporation of the radio-opaque marker was associated with a significant enhancement in technical simplicity compared with similar procedures conducted without it. The patient was discharged the following day with complete fenestration closure and no complications.